1. Field of the Invention
The present invention relates to computer-aided aircraft navigation methods and systems employing such methods.
2. Description of Related Art
Currently, aircraft pilots, particularly pilots of small aircraft such as “VFR” aircraft, are permitted significant latitude in choice of flight path and altitude between the origin and destination of a given flight. At the same time, small aircraft are relatively prone to engine failures that require emergency landing under no power. In addition, fuel system malfunctions or leaks, and fuel mismanagement or miscalculations, can impact aircraft of any size. Under the proper weather and landing conditions, small aircraft are designed to be controllable without engine power, and can be glided to a safe landing. Even larger aircraft may be capable of making a survivable landing after suffering a loss or reduction of power. To accomplish a safe landing, it is necessary that an acceptable landing area be available within a defined maximum glide distance of the location where engine failure occurs. The maximum glide distance depends mainly on the glide characteristics of the aircraft, the aircraft altitude when engine failure occurs, aircraft airspeed and altitude at all points of the descent, and altitude, temperature, wind speed and direction.
Under emergency or non-emergency conditions, selection of the best acceptable emergency landing area is rarely trivial, and mistakes can be fatal. The calculation of maximum glide distance is prone to error, and the availability and location of acceptable emergency landing areas is often unknown. The identification of an acceptable landing area can be significantly complicated if the aircraft is in, or above, conditions that obscure or limit the pilot's ability to view the ground, if the aircraft is flying at night, or if the aircraft is over rough terrain. Similarly, if the aircraft is over an area with numerous roads, some of which are acceptable for landing and others are not (for reasons such as power lines crossing the road, insufficient road width and obstacle clearance, etc), or in other conditions, the pilot may incorrectly identify a landing target only to determine, when he is too close to the ground to pick another target, that the intended landing target is not in fact safe. Current navigation equipment does not adequately assist aircraft pilots in the selection of emergency areas, in the event of engine failure.
Furthermore, a pilot in an emergency landing situation often is in the position of being able to make only one approach to the landing site. If the pilot picks the wrong glideslope, approach speed, or other aspects of the approach, the pilot may overshoot or undershoot the target. While the likelihood of such a “miss” is increased in poor visibility or significant wind conditions, it is present even in clear weather as pilots rarely practice “power-off” landings all the way from a cruise altitude to the ground.
In addition, prudent flight planning would plot a course and altitude so as to keep the aircraft, to the extent possible, within a safe gliding distance of an emergency landing area at all times during the flight. However, the information gathering and calculation required to perform this task are too burdensome to permit detailed consideration of emergency landing in flight planning. Pilots therefore miss opportunities to navigating aircraft so as to minimize the likelihood that an emergency landing will not be successful. It would be desirable, therefore, to provide a tool whereby the chances of a successful emergency landing may be improved via prudent navigation.